486 MR. A. G. BUTLER ON [Nov. 4, 



In Aden the Catopsilice appear to be very common, thirty-nine 

 specimens being in the present collection. The females separate 

 readily into four types ; but as regards the males I agree with Major 

 Yerbury in admitting that " I have found it very difficult to separate 

 the different Catopsilice." They have, however, enlightened me 

 upon one point, which is, that the males of 0. pyrene and C. fiorella 

 (as in many other species of Callidryas) are extremely similar, 

 whilst the females are entirely different ; that, consequently, Bois- 

 duval was in error as to the male of the latter species, whilst my 

 friend Trimen was partly right and partly wrong. The male of 0. 

 fiorella is indeed white and very like that sex of 0. pyrene ; but I 

 have little doubt of its distinctness from that species in Tropical 

 Africa, though in Aden I have every reason to believe that 0. pyrene, 

 C. aleurona, and 0. fiorella are one species ; this opinion I base not 

 only upon the fact that all fly together (for that is not conclusive 

 evidence of identity), but from the existence in Aden of a fourth 

 form between C. pyrene and C. aleurona and perfectly intermediate 

 on both surfaces. This intergrade, which I believe to be M. Bois- 

 duval's C. hyblcea described from a Senegalese specimen, resembles 

 C. rufo-sparsa of Madagascar and C. gnoma of India on the upper 

 surface, but on the under surface is only a little yellower than C. 

 pyrene, with similar greyish reticulations and barely a trace of the 

 discal series of spots. 



If in Tropical Africa C. fiorella were merely a dimorphic form of the 

 female of C. pyrene, as Mr. Trimen clearly supposed it to be, there is 

 no reason why intergrades between the females should not occur com- 

 monly with them there, as at Aden ; yet this is not the case. On the 

 other hand, admitting the distinctness of the two species in Southern 

 and Western Africa, the fact that they are one species in Aden can be 

 explained by the not improbable supposition that the Abyssinian 

 type has steadily migrated in that direction, and, being almost exactly 

 intermediate between the two, has rendered the preservation of a 

 tetramorphic species possible in this case as in that of Limnas chry- 

 sippus ; nor in my opinion is such a supposition at all fanciful in the 

 case of genera which are notorious for the possession of a strong 

 migratory instinct. 



In the present paper I must necessarily treat the forms of Cato- 

 psilia as I have done those of Limnas. 



19. Catopsilia florella. 



2 Papilio fiorella, Fabricius, Syst. Ent. p. 479, n. 159 (1775). 



Callidryas (Catopsilia) fiorella, Butler, Monogr. in Lep. Exot. 

 p. 56, pi. xxii. figs. 1, 2, 2 a (1871). 



cJ, Aden, 26th February, 1883; ?, 27th March, J, 14th April, 

 1884 ; d 1 , Lahej, 3rd April, 1884. 



The males are larger than those of C. pyrene, have the primaries 

 more produced, with incurved outer margin rather distinctly spotted 

 with smoky grey ; on the under surface also the angular discal sub- 

 apical streak is tolerably distinct. 



